The subject matter disclosed herein relates to the protection of fluid probes in harsh operating environments. More specifically, the present disclosure relates to a sheathing for fluid probes adapted for use in turbomachine fluid flow paths.
In turbomachines, such as gas turbines, the properties of an operating fluid may substantially affect the performance characteristics (e.g., efficiency) of a turbomachine assembly. Many turbomachines include several stages which extract energy from successively lower-pressure operating fluids. In a low pressure stage of a turbomachine, even minor changes in an operating fluid's pressure, temperature, and/or fluid velocity can cause high percentage changes to the turbomachine's performance. Various probes can be installed within a turbomachine to measure operational parameters, e.g., temperature, pressure, and/or flow rate, of fluids within the turbomachine during operation.
Fluid probes are reliable measuring instruments, but may experience wear after extended use. Fluid probes adapted for use in a fluid flow path of a turbomachine, e.g., a hot gas path portion of a gas turbine, may be susceptible to wear from elevated temperatures and/or exposure to reactive or catalyzing particles within the fluid flow path of the turbomachine. One or more protective devices or instruments can be deployed to protect fluid probes from such conditions, but conventional structures may interfere with the operation of the probe and/or rely upon materials with other disadvantages. Metallic covers for fluid probes, for example, can exhibit high thermal conductivity and/or may chemically react with the turbomachine fluid to produce corroded material and/or deposits during use over extended periods. In some cases, metallic covers and/or other metal components formed from less-expensive materials may eventually lose material strength when operating at elevated temperatures over a long time. Some otherwise acceptable metallic coverings may be expensive to produce, and thus may not be practical for large numbers of turbomachines.